The present disclosure relates to an apparatus for driving converters in a wind power generation system, an apparatus for controlling converters in a wind power generation system, an apparatus for driving switching element modules in a wind power generation system, and an apparatus for controlling switching element modules in a wind power generation system. More particularly, the present disclosure relates to a technology for driving a converter in response to current grid output by sequentially driving the converters as power output to a grid is increased and sequentially stopping the operation of the converters as power output to the grid is reduced, a technology for improving the lifespan of a converter by making identical the operation times of a plurality of the converters that are connected in parallel in a wind power generation system, a technology for driving switching element modules in response to the amount of power currently output by converters by sequentially driving the switching element modules one by one when output power of the converters is increased and sequentially stopping the operation of the switching element modules one by one when output power of the converters is decreased, and a technology for reducing a harmonic component included in an alternating current (AC) generated by a converter by making different points of time at which a plurality of switching element modules included in the converter is driven.
A wind power generator converts kinetic energy of the wind into mechanical energy attributable to the rotation of a blade. The converted mechanical energy is converted into electric energy through a generator.
A converter disposed between the generator of the wind power generator and the grid includes only a single switching element module. When the wind blows, the blade of the wind power generation system rotates. Kinetic energy attributable to the rotation of the blade is converted into electric energy through the generator. The electric energy converted and generated by the generator is AC power. The AC is converted into a direct current (DC) by the switching element module included in the converter. The DC is converted into an AC to be supplied toward the grid.
In a conventional technology, no matter how weakly the wind blows, all of a plurality of converters operates. Accordingly, efficiency of power versus consumption power of the converters, which is output by a grid in accordance with the velocity of the wind, is low.
It is desirable to reduce output power supplied to the grid versus power consumed by the plurality of converters in accordance with the velocity of the wind by driving only some of the converters or all of the converters in response to the high or low of power output to the grid.
Furthermore, a plurality of converters may be disposed between the generator of a wind power generator and the grid. When the wind blows, the blade of the wind power generator rotates. Kinetic energy attributable to the rotation of the blade is converted into electric energy through the generator. The electric energy converted and generated by the generator is AC power. The AC is converted into a DC by the converters. The DC is converted into an AC to be supplied toward the grid.
When the wind blows, any one of the plurality of converters is to be driven according to the aforementioned process. In a conventional technology, a converter that is always first driven has been predetermined. Only one of the plurality of converters is driven unless the generator generates high power as the velocity of the wind increases. Accordingly, there is a problem in that the lifespan of the converter that is frequently driven is reduced.
Furthermore, there is a problem in that the lifespan of a converter that is always driven is reduced because the predetermined converter is always driven even in a situation in which two or more converters have to be driven.
It is also desirable to reduce output power supplied to the grid versus power consumed by a converter in accordance with the velocity of the wind by driving only some of a plurality of switching element modules or all of the switching element modules in response to the high or low of power output by the converter.
Furthermore, when the wind blows, only a single switching element module included in a converter is to be driven according to the aforementioned process.
In this case, if the switching element module driven by a pulse width-controlled method is turned off, an electric current is reduced. The electric current slowly decreases when inductance of the inductor of a filter connected to the output stage of the converter is great. If an inductor having great inductance is used to slowly reduce the electric current, the size of the filter becomes bulky and a cost is also increased.